Efficient, reliable, and real-time communication with minimal latency is a critical requirement for public safety organizations and first responders. Inasmuch, the Telecommunications Industry Association (TIA) adopted and standardized a suite of Land Mobile Radio (LMR) standards termed Project 25 (P25), as described for example, in the TIA 102-series documents. The emerging P25 standard defines the operation and interfaces of P25-compliant radio systems. Specifically, and in part, the P25 standard defines a standard for trunked systems.
A “trunked system” or “trunked network” is defined as a radio system where a limited number of frequencies or “traffic channels” are shared among a large group of endpoints (wherein “endpoints” are also interchangeably referred to herein as users), and the traffic channels are dynamically assigned as needed using a control channel. This is in contrast to a “conventional” communication system, which typically uses a dedicated channel for each group of endpoints. Trunked systems are particularly beneficial in specific instances where there is a limited number of available communication frequencies, but a large group of endpoints use the system for communications. Each group of endpoints within a trunked system is assigned to a virtual channel or “talkgroup” having a group identification (group ID) where, inherently within a trunked system, the number of talkgroups usually exceeds the number of available communication frequencies. Often, upon assignment of a group ID, large numbers of endpoints are assigned to that talk group ID, and all endpoints communicate through the use of “shared” keys.
Many law enforcement agencies, fire departments, and other public safety organizations currently use shared keys provided by trunked systems to relay critical voice communications. To provide the best level of confidentiality protection, each pair of endpoints ideally shares their own unique key, with the key being “unique” in that it is different from the key shared by any other pair of endpoints in the communication system. However, in systems where there are hundreds, thousands, or tens of thousands of endpoints, it is not practical to manage unique keys for every possible point-to-point communication pair. As a result, radio system administrators typically configure the radio endpoints to use a common group key for secure, point-to-point calls. The common group key thus ensures that each device has the appropriate key when communicating with a different device. However, the disadvantage is that the confidentiality of the communication session is not protected from all other endpoints in the system that possess the same group key; and one or more of these other endpoints may inappropriately intercept communications between the established point-to-point communication pair.
Accordingly, there is a need for methods for establishing secured point-to-point communications on a trunked network.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of various embodiments. In addition, the description and drawings do not necessarily require the order illustrated. It will be further appreciated that certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required.
Apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the various embodiments so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. Thus, it will be appreciated that for simplicity and clarity of illustration, common and well-understood elements that are useful or necessary in a commercially feasible embodiment may not be depicted in order to facilitate a less obstructed view of these various embodiments.